More seniors on Medicare use antibiotics: study

More seniors used antibiotics after enrolling in Medicare Part D, the program that helps pay for prescription drugs, in a new study of about 35,000 people.

The results are promising for conditions like pneumonia, which is sometimes deadly in the elderly but can be effectively treated with antibiotics, the authors say. But study participants with viruses also took more antibiotics - which don't do anything against those types of infections.

Unnecessary use of antibiotics contributes to resistance - when bacteria build up immunity to these drugs and the drugs are no longer effective.

The more antibiotics that are used - when they're needed and when they're not needed - the more likely bacteria are to become resistant to the drugs. Resistant infections can then spread so that more and more people have conditions that no longer respond to certain antibiotics. Resistant cases are often more dangerous and more expensive to treat.

In many cases, Zhang told Reuters Health, "patients didn't know that by taking those drugs, sometimes they won't be helpful."